Tuesday, June 16, 2009

Leaf display in motmots

Wakako is here with me for two weeks, and on a walk here at the Laguna de Apoyo a few days ago, she and I observed a Turquoise-browed Motmot performing the so-called Leaf Display. This is a curious behavior that is known from at least four of the ten motmot species (Murphy 2008). Use of inedible props has been described for only four avian groups: bowerbirds, fairy-wrens, birds-of-paradise, and the Central American motmots. In the first three taxa, the use of props plays a role in mate acquisition and is associated with males only, but in the case of motmots, both sexes exhibit this behavior and its use appears to be less specific, possibly associated with intraspecific aggression or with status (Murphy 2008).

This behavior is performed by paired and unpaired birds alike, during and outside the breeding season (Murphy 2008).

I have seen it many times myself. Usually what happens is that I will hear several motmots calling from a spot, then the calling reaches a feverish pitch and as I sneak up on them, I will find several birds sitting in the same tree, often with one individual holding a leaf in its bill. Many times, the leaf holder will remain in its place as other individuals fly off, which appears to confirm the aggression / status interpretation. Evidently, when you're a motmot, one of the worst things that could happen to you is being confronted by another motmot holding a leaf in its bill, showing you who is boss. These are curious birds, indeed.

Here's a picture of a Russet-crowned Motmot with a small green leaf in its bill. According to Murphy (2008), it is more common for motmots to use bigger and older (brown or yellow) leaves. I photographed this bird, a Mexican endemic, last summer when I assisted Troy Murphy with work on Streak-backed Orioles in the Sierra de Huautla, in the Mexican state of Morelos.

If you're interested in the article cited above, go here for a download link.

Cited literature:
Murphy, Troy (2008) "Display of an Inedible Prop as a Signal of Aggression? Adaptive Significance of Leaf-Display by the Turquoise-browed Motmot, Eumomota superciliosa" in Ethology 114: 16-21, Blackwell Verlag, Berlin.

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